Aircraft alighting gear



' upper portion of* an elem-pneumatic at Patented Jan. 9, '1945 ATRCRAFTHLIGH'IYINGBEKR .RowlandeHenry tBou-nd, Cheltmbam; r Englgndfi s Claims. (01. eta-910421;

This -inventio'n is 'an aircraft landing element mounting whichpermits ysteering *or eastdzing of the "landing element and which "employs shimmy damping means to resistand thereby "adamp ou-t smallrapid angulardisplacements of'the landing element" i It is an obj ect of the present invention "to' -pro-= vide *a compact and-satisfactory arrangement "of shimmy :damping means foran elem-pneumatic shock-absorber strut which shimmy v damping mean-s utilises the fluid -enclosedwith-in the "strut to provide the resilient *resistance required 'for landing"and-taxiing-loadsfi It is a further =obje'c t of' the present: inventien to provide satisfactory "damping 'means which in *operaticn intertere neithe't with thenormal resilient I characteristics' of the -stnut 'nor with 1 any Self-centering means such as are generallif provided-in steerable or caste-table iaircraft landing=elementmountingsu- The invention has amartieular embodimenti in an auxiliary la nd'ing L element mounti'n'g suo h as that for a1taiil landingelement:nr tliemose or rear landingelementRot-t1* tricycle undercarriagei The inventiomwill mow be described with ref-' 'erence tetheaeccm eanzting diagrammatic draw;

in in Which??- 1 is a -sectional: si'de elevation of-irlthe mounting?Fiesta'is 'aisimilar view of. th 1 i portionfthe mountings Figure f :2 'is a side i elevation 0f l the :ashimmy damping piston incorporated ins $116. immunizing; and i FiguresB ista pla'n view cnrrespon-dingrto Fig-f ure 2.

Referring a now -:to "the drawing, the ao'leo-tpnem matic tail wheelirnounting illustrated :wembadies dtr'ection oi' traveh The-'ceaxially extendmg ,reunseat-extension I0 of. it-he sleeved is'--open atwitfs" lower :end ,and'jreceives the ilo'eatihg pin '-;l I -ex r tending up from "the "rotatable part -i 6 *of I the I mounting: the "projection HI i being "squared for splihed for 'the re eeptio-m of "the *shimm-y damp e ing piston ili. Anidle anama is provideidwinternalli *cF-the upper'fixed A sleeve -pa-rt 8 to-'define between :the end closure plug l andthe idle {piston 13 the air chamber" 14 to whichairi on'gasat pres sure is. introduced through theinflation*valve Hi Thewlowerpart ofthestrut'beyond the idle piston It "is "filled with "'liquid'::i-nt1oduced through the an "outer strutpantA 'Whichrfisi noneyieldingsunder landing and taxiing loadsflbut which-is prefers ablywmounte'd to .swing for: retnactionz-ipunpeses about'ithe raxisrof thefzlugrfitting =15, retraution being feffectedmy means 1of;a: remotely? contmlla= ble jack (not shown). The non-yieldingrrsle'eue part4 teceives iritemallylathe:yielding and rotatable sleeve part 6. At its upper end the sleeve part 4 is plugged, as indicated at 1. From the end plug I there extends coaxially an internal fixed sleeve part 8, which is ported to provide restricted passage for fluid flow, as will later be apparent. The port arrangements, in accordance with the usual procedure for damping oleopneumatic struts, include a clack valve 9, the arrangement of which is such as to provide dif- ,ferential damping effect in accordance with the other hand' when th'e stl utfis supportiti-gvtheair-a craiftggets irrthe chamber :14 is ficompressed liquid having"beeniforced throuefih the ponts zkxitzi and 26' as the sleeve part-"fi {yields with-respect td the outer sleeve par-M4 and in consequence aof the relative movement betweenuthe fixedrandiyields able" sleeve parts-the iedge ieamrzo Eseparatesrsfrom the edge earn! 9 iwith the resultl'that'the landing element 'is complete-1'9 fl eestomastmrnataall' times when *itas simporti'ng (the aircraft :omthe gnou-ml. shimmy damping the gshimmyt damping piston-1 l 2 slides omtha-squanew extensiontzlzfl land ismrovidd-Wvithlsazzsinuous camssl'otwzfl Whit-lads engaged byanea ner i 28 ziextendihg ainho :iit'. :ftom the yieldabl'e and' rotatablesleeue'npant :The shimmydampirigepistdn 2 lhas asdampingrzpant 29 ext-e'nding rig ht thmughiit iandtit will herein...

ised that due to the interengagement of the roller 28 with the cam slot 27, small and rapid angular movements of the landing element resulting from shimmy are translated into reciprocation of the damping piston I2, which movement is effectively damped by the restricted. passage for fluid through the port 29.

i In some cases springs may be loaded on either side of the shimmy damping piston, in which through the liquid 1. In a mounting for an aircraft landing element, a strut part for connection to the aircraft, a strut art to mount a landing element assembled with said first strut part for rotation relative thereto about an axis extending lengthwise of the strut, and said strut parts being relatively yieldable axially against resilient resistance under landing and taxying loads, a damping piston,

means interengaged between said damping piston and said first strutpart restraining relative ro-. tation thereof but guiding said piston and first strut part for unrestrained relative axial resaid strut parts effected by landing and taxying loads, and cam means interengaged between said damping piston and said second strut part,- including a sinuous groove in one such element and a projection carried by the other element and received in said groove, for effecting relative axial movement .-of said second strut part and said damping piston against resistance by relative rotative displacement of said strut parts, whereby to tend to damp out landing element shimmy.

2. A mountin-g as set forth in claim 1, wherein the second strut part is hollow and contains liquid in which the damping piston is; submerged, and the damping piston has therethrough a restricted aperture resisting liquid flow through it during relative axial movement of the-damping piston and the second strut part. I

3. An oleo-pneumatic strut, for mounting an aircraft landing element, including a strut part for connection to the aircraft,-; a hollow strut part to mount a landing element assembled with said first strut; part to'definetherewithin a closed space containing liquid and h air, and rotatable relative,.,t o'-said first strut part about an axis lengthwise-of the strut, said twostrut parts being yieldable axially under. landing and taxying loads against the resilient resistance of the oleo-pneumatic medium within such space, a non -rotatable shimmy damping piston received in said hollow strut part, submerged in' the liquid therein, and havinga restricted port therethrough communieating with theliquid at each 'end of said piston, means interengaged between said piston and said first strut part guiding the same for unrestrained relative reciprocation during relativ axial movement of said strut parts effected by landing and taxying loads but restraining relative rotation thereof, and means interengaged between said piston and 'saidyhollow strut part for effecting axial movement of said piston relative to said cylindrical. strut part, and thereby forcing it therein, b relative rotation of said strut parts, whereby to tend to damp out small and rapid angular displacements of the landing element during taxying.

4. In a mounting for an aircraft landing element, a strut part for connection to the aircraft,

' a strut part to mount a landing element assembled with said first strut part for rotation relative thereto about an axis extending lengthwise of the strut, and said strut parts being relatively yieldable axially against resilient resistance under landing and taxying loads, a damping member freely slidable relative to one strut part during such relative axial movement of said parts effected by landing and taxying loads, and means ciprocation during relative axial movement of in, means interconnecting said upper cylinder and interconnecting said damping member and the other strut part for eifecting relative axial movement thereof against resistance by relative rotative movement of said strut parts.

5. In a mounting for an aircraft landing element, a strut part for connection to the-aircraft, a strut part to mount a landingelement assembled with said first strutpart for rotation relative thereto about an axis extending lengthwise of the strut, and said strut parts being relatively yieldable axially against resilient resistance under landing and taxying loads, a damping piston, means interengaged between said damping piston and-said first strut part restraining relative rotation thereof but guiding said piston and first strut part for unrestrained relative, axial reciprocation during relative axial movement of 'said strut parts effected by landing and taxying I aircraft landing element, including a hollow upper cylinder for connection to an aircraft, a hollow lower cylinder carrying a landing element and telescopically engaged with said upper cylin-,

der for rotation and reciprocation relative thereto, said two cylinders cooperatively defining therewithin a space containing liquid and air, and means for damping relative rotation of said cylinders without offering resistance to relative reciprocation thereof, including a piston havin a restricted orifice therethrough received in said lower cylinder and submerged in the liquid theresaid piston and guiding the same for unrestrained relative reciprocation during axial movement of said strut parts effected by landing and taxying loads but restraining relative rotation thereof, and means interengaged between said piston and said lower cylinder for effecting reciprocation of'said piston relative to said lower cylindenand thereby forcing it through the liquid therein, by relative rotation of said cylindrical parts, whereby to tend to damp out small and rapid angular displacements of the landing element during taxying.

' ROWLAND HENRY BOUND. 

